Coextruded fluoropolymer/polyamide laminate

Abstract

Coextruded layers of polyamide and fluoropolymer adhere to one another without an intervening tie layer by adhesive activation of polyamide of the polyamide layer, e.g. by incorporating into the polyamide layer a dispersed phase of maleic anhydride-grafted ethylene/propylene/diene copolymer. The fluoropolymer is a copolymer of ethylene with perhalogenated comonomer or a copolymer of tetrafluoroethylene with perfluorinated comonomer.

What is claimed is:  
     
       1. Coextruded laminate comprising a layer of fluoropolymer directly adhered to a layer of polyamide in the absence of any tie layer between said layers, said fluoropolymer being a copolymer of tetrafluoroethylene with perfluorinated comonomer or a copolymer of ethylene with fluorine-containing perhalogenated monomer, at least said polyamide having been adhesively activated to form said coextruded laminate, said layer of fluoropolymer forming a surface of said laminate, wherein the adhesive activation of said polyamide is obtained by said polyamide having a polymeric additive incorporated therein prior to said coextrusion, said additive having polar functionality. 
     
     
       2. The coextruded laminate of  claim 1  wherein said polar functionality is anhydride, acid, ester, or salt of said acid, or epoxy. 
     
     
       3. The coextruded laminate of  claim 1  wherein said fluoropolymer is adhesively activated. 
     
     
       4. The coextruded laminate of  claim 1  in the form of composite tubing. 
     
     
       5. The coextruded tubing of  claim 4  wherein the inner layer of said tubing is said layer of fluoropolymer. 
     
     
       6. The coextruded tubing of  claim 5  wherein the thickness of said layer of fluropolymer is less than 8 mils. 
     
     
       7. Process comprising coextruding fluoropolymer and polyamide into layers in the absence of any tie layer between said layers so that said layers are in direct contact with one another, said fluoropolymer being a copolymer of tetrafluoroethylene with perfluorinated comonomer or a copolymer of ethylene with fluorine-containing perhalogenated monomer, said polyamide having been adhesively activated so as to adhere said layers to one another, said layer of fluoropolymer forming an exterior surface of the resultant coextruded laminate, wherein the adhesive activation of said polyamide is obtained by said polyamide having a polymeric additive incorporated therein prior to said coextrusion, said additive having polar functionality. 
     
     
       8. Coextruded laminate comprising a layer of fluoropolymer directly adhered to a layer of polyamide, said polyamide of said polyamide layer having been adhesively activated to form said coextruded laminate, said fluoropolymer being a copolymer of tetrafluoroethylene with perfluorinated comonomer or a copolymer of ethylene with fluorine-containing perhalogenated monomer, the adhesive activation of said polyamide being obtained by said polyamide having functionalized fluoropolymer incorporated therein prior to coextrusion to form said laminate. 
     
     
       9. Process comprising coextruding fluoropolymer and polyamide into layers in the absence of any tie layer between said layers so that said layers are in direct contact with one another, said fluoropolymer being a copolymer of tetrafluoroethylene with perfluorinated comonomer or a copolymer of ethylene with fluorine-containing perhalogenated monomer, said polyamide having been adhesively activated so as to adhere said layers to one another, said layer of fluoropolymer forming an exterior surface of the resultant, coextruded laminate, wherein when the adhesive activation of said polyamide is obtained by incorporating functionalized fluoropolymer therein prior to said coextruding. 
     
     
       10. The coextruded laminate of  claim 1  wherein said polymeric additive is selected from the group consisting of functionalized fluoropolymer and ionomer. 
     
     
       11. The coextruded laminate of  claim 1  wherein said polymeric additive is elastomer, said elastomer having said polar functionality.